Balance wheel amplitude controlling device



March 26, 1957 c. JORIOT BALANCE WHEEL AMPLITUDE CONTROLLING nnvxcz:

'' Filed Dec, 17, 1954- 2 Sh eets-Sheet 1 1w l/EN To}? CAM/4.45 JOE 07" March 26, 1957 c, JORIQT 2,786,329

BALANCE WHEEL AMPLITUDE CONTROLLING DEVICE Filed Dec. 1'7, 1954 2 Sheets-Sheet 2 I- vs/v 772R.-

CAM/4,45 yak/07 United States Patent 2,786,329 lc Patented Mar. 26, 1957 BALANCE WHEEL AMPLITUDE CONTROLLING DEVICE Camille J oriot, Villers-le-Lac, France Application December 17, 1954, Serial No. 480,654

Claims priority, application France December 24, 1953 8 Claims. (Cl. 53-121) The present invention relates to improvements in timepieces and refers to means adapted to materially minimize the variations in the amplitude of the oscillations of a balance wheel of a timepiece under the action of various causes in order to improve the regularity of the rate of the watch or timepiece.

Actually, irregularities in the rate of a watch are due to the lack of isochronism, i. e. variations in the period of oscillation of the balance wheel, which period is a function of the amplitude of this oscillation fora given balance wheel. Therefore, it ensues that any means adapted to minimize the lack of isochronism, should either directly or indirectly bring about a stabilization in the value of said amplitude.

One of the primary objects of the present invention is to provide means cooperating with the conventional regulating members of a watch capable of achieving the above mentioned effect by means of a direct action upon the balance wheel.

Such means or device mainly comprises a movable damping member in the shape of a blade mounted for pivotal movement on an axis located between the axis of the pallet and fork and the axis of the balance wheel, adapted to assume upon each stroke of the fork an invariable position from which a striking pin secured to the safety roller of the balance wheel strikes said damping member whenever the amplitude of the oscillations of the balance wheel are in excess of the normal value which corresponds to the perfect rate. The balance wheel is then subjected to an antagonistic torque created by the inertia of the damping member which is displaced by the balance wheel only a short distance. Therefore, the amplitude of the oscillations of the balance wheel is maintained near the optimum value within very close limits.

Both distinct actions above mentioned are achieved in the following manner:

On one hand, the fork acts upon the movable damping member and drives the latter along as it approaches one or the other of its banking pins, by means of an intermittent unilateral connecting mechanism consisting, for instance, of a finger rigid with the fork and extending through an aperture of suitable dimensions provided through the blade, whereby the stroke of the finger between the opposite edges of said aperture is shorter than the entire stroke of said finger in the course of a complete oscillation of the fork.

Such a connecting mechanism causes the damping member to be adapted to assume to rest or recoil positions which are accurately determined and invariable, whenever the fork engages its banking pins while allowing it to freely move outwardly a distance which depends on the width of the aperture. This freedom of complementary movement is used in only one of the two positions, under the action of the striking pin above-mentioned, because of the particular shape given to the end or nose of the damping member which makes it possible for the pin to engage said nose in one direction only.

This pin secured at a point so located that, when the amplitude of the oscillations of the balance wheel is normal, it gently engages without any shock the nose of the damping member at the end of the forward stroke of the balance wheel, said nose, at that moment, assuming one of its invariable rest or recoil positions above mentioned.

Therefore, when the stroke of the balance wheel is in excess of the normal one, since the pin tends to further travel it strikes upon the damping member which receives this blow from the side opposite the fork banking pin near which it is at rest and therefore is able to be moved under the action of the pin. Hence, the rate of the pin is slowed down (or damped) due to the inertia of the damping member. This damping effect will be more or less acute and the virtual excess stroke more or less reduced according to the relative values of the moment of inertia of the damping member about its axis and the distance between the striking pin and the geometrical axis of the balance wheel. Experience shows the optimum values to be given thereto in order to secure the desired result.

In any case, the stroke of the striking pin will be limited by the extreme position the damping member is able to assume, namely that corresponding to its abutting against the fork banking pin, or preferably against an adjustable additional abutment.

Though such a limitation of the stroke occurs at one only of two half-oscillations, i. e. every other stroke, in the course of the forward strokes for instance, obviously, the other half-oscillations, namely the backward strokes, take a part in the limitation imposed upon the former. Thus, the period of oscillation will be able to keep very near the perfect rate period, even within very wide limits for the virtual Variations of the amplitude. This has been proved by experience and may be explained by the reason that, due to a damped impact, the striking pin travels but a short distance beyond the point of impact namely the end of the normal stroke, and also by this further reason that the remaining excess of the effective amplitude of the oscillation over the normal one finds a compensating effect in the greater speed of a similar balance wheel rotating an equal central are when the amplitude of its oscillation increases.

Other objects and advantages of the invention will be apparent to those skilled in the art, from a consideration of the following description of some specific embodiments of the invention, shown by way of example, in the accompanying drawings, in which:

Fig. 1 is a sectional view of a normal regulator of a timepiece completed with the automatic regulating device (line or section offset to the right between the wheel staff and the striking pin).

Fig. 2 is a top view of the movable damping member.

Fig. 3 is a bottom plan view of the pivot-screw of the damping member.

Fig. 4 is a top plan view of a fork in modified form used in the invention.

Fig. 5 is a bottom plan view of a modified balance wheel showing only the roller table, the safety roller and their equipment.

Figs. 6 and 7' illustrate two relative positions of the clamping member and fork corresponding to the drive of said damping member in either direction.

Fig. 8 is a top plan view of the parts for the automatic regulation at the end of the forward stroke of the balance wheel for a normal amplitude.

Fig. 9 is a partial top-view of the same parts, at the end of the forward stroke of the balance wheel for a virtual amplitude in excess of the normal one.

Fig. 10 is a similar view of the positions obtained for very great amplitudes.

Fig. 11 is a top view of the same parts at the moment when the fork hits its left-hand banking pin and the striking pin passes the nose of' the damping member.

Fig. 12 is a top view of a first modification of the fork and damping member (abutment for the damping member not shown).

Fig. 13 is a section taken on line Xl-ll- '11! of Fig. 12.

Fig. 14 is a top plan view of a further modification of the fork and damping member.

Fig. 15 is a section taken on line XV-XV of Fig. 14.

Referring now more particularly to the drawings, there is disclosed a movable damping member forming a relatively thin blade 1, which is made of uniform thickness throughout and of a suitable metal, said blade having a sleeve 2, preferably in the form of a jewel for receiving a pivot. The geometrical axis 2a of said sleeve extends through the center of gravity of said blade. The pivotscrew 3 of the clamping member 1 and the shafts 4 and 6 of the balance wheel and the fork 7, respectively, have a common diametrical plane. This screw 3 which has a wide head 3:: is secured to the platen 8 of the watch through the medium of a tapped support 9 made of hard-steel the upper end surface of which is mirrorpolished, so that the blade is maintained as to its height and may be moved with friction reduced to a minimum.

The blade 1 positioned under the fork 7 has one end thereof located under the safety roller 5a of the balancewheel and formed into a bevelled nose 1a and the opposite end thereof 1b has a Wide notch, so that the blade is able to oscillate sufliciently without interfering with the fork spindle 6.

The fork 7 has a dependent cylindrical projection 11 hereinafter called driving finger position under the toe of the guard pin which extends through a square aperture 12 of the blade, substantially on the middle line thereof. The side 12a of said aperture 12 has a length smaller than the stroke of the finger 11 as determined by a complete oscillation of the fork, but, long enough for permitting a sufiicicnt independence in the movement of the damping member relative to the fork, as it will be made clear presently in the description of the operation of the device.

A striking pin 13 is secured to the safety roller 5a at a determined angular distance from the pin 14 of the roller table 5b in such a manner that, at the end of a forward stroke of normal amplitude, said pin 13 comes gently into engagement with the nose in of the damping member which is then in one of its two rest positions which is involved in the operation.

An abutment 16 for the damping member, constituted by an eccentric smoothly fitted within a bore of the pillar plate, and the position of which may be adjusted by means of a turn screw blade, completes the present device.

The operation of the device is as follows:

When, under the impulse of the escapement, the fork 7 is thrown toward its right hand banking pin a, it carries with it from a given point of its right-hand half stroke (Fig. 7) the movable damping member 1 through the driving finger 11 which comes into bearing engagement against the right-hand side of the square aperture 12 and thus causes the nose 1a to assume a position which is well determined when the fork comes to a rest against its banking pin 15a, as indicated in Fig. 8.

Simultaneously, the balance wheel reaches the end of its forward stroke and the pin 13 is, according to the invention, secured at a point such that when the oscillation of the balance wheel has a normal amplitude, it gently engages the nose 111 at the end of the stroke.

First under the action of the hair-spring, the balance wheel starts for its backward stroke and initiates the return movement of the fork which almost immediately receives the power impulse from the escapement Wheel.

The roller jewel 14 enters the slot 7a of the fork, and the finger 11 comes into engagement with the left-hand side of the square aperture 12 (Fig. 6) in order to carry it leftward until the fork stops against the banking pin 15b. it should be noted (Fig. 11) that, during the backward oscillation, while the damping member is at rest, the nose of the clamping member is so designed that the striking pin 13 freely passes said damping member without running the risk of hitting it.

The balance wheel now at the end of its backward stroke begins a forward stroke and the striking pin 13 again passes freely the nose of the damping member which is then in its left-hand rest position. The fork then sweeps to the right and brings the damping member 1 back to the position it assumed at the end of the preceding forward stroke, as indicated in Fig. 8, and where again it will be gently engaged by the pin 13 at the end of the constant stroke.

The cycle occurs repeatedly in an identical manner as long as the amplitude of the oscillations of the balance wheel has the same value.

Should this amplitude become smaller, it is clear that nothing is changed as far as the extreme positions assumed by the damping member 1 are concerned, the only difference lying in the fact that the striking pin 13 no longer engages the nose in but keeps more or less distant from said nose at the end of a forward stroke.

If, in contradistinction, the amplitude of the oscillations of the balance wheel tends to exceed the normal value, the pin 13 hits the nose 1:! of the damping member prior to the end of the forward stroke; the damping member opposes the progression of the balance wheel due to its inertia. Said pin 13 thus comes to a standstill in a position which is variable according to the increase of amplitude that the balance wheel would normally effect if no damping device were provided, but the limit of which, obviously, is the positive stop position imposed by the extreme position that the damping member is able to assume toward the right, and corresponding to the contact of said damper with the damper abutment 16, as indicated in Fig. 10, the size of the square aperture 12 being suficient for allowing said displacement if need be.

This limit position very seldom will be reached, owing to the inertia of the movable damping member which is sufficient for strictly limiting the damped amplitude, whatever the value of the virtual amplitude.

The selection of the inertia of the damper is of great importance. In the course of the tests carried out with a calibre 10 /2 size watch in lignes, the volume of the movable damper adopted was 250,000 hundreths of a cubic millimeter. In this case, there was obtained a sharp correction of the retardation created by the long arcs, whereas such correction was yielding with 225,000 and excessive with 275,000 hundredths of a cubic millimeter.

In the above specified conditions, it is possible to check that, when the main spring is wound-up one turn, the amplitudes are between 220 and 230; when the spring is completely wound-up these amplitudes are still very near 235 and do not vary in excess of 10 during thirty hours running, whereas their variations reach within the same interval of time, when the device is not incorporated. It is possible to obtain a stabilization of the amplitude of the same order near 250, 255 or 260 by changing the location of the striking pin 13 and by increasing the power of the main spring.

In some watch sizes, it is more desirable to obtain amplitudes as near 270 as possible and also to cause the damper to be driven by the fork after the latter has created the impulse to the balance wheel, i. e. after about the sixteen twentieths of its total stroke between the two banking pins, in both directions.

It goes without saying, and it is understood from the above, that the invention is in no way limited to the embodiments described nor to the designs of the various parts thereof.

In fact, apart from the preferred embodiments above indicated, it is possible to conceive in various manners a device adapted to limit the stroke of the balance wheel as soon as it tends to exceed the normal value, these results being achieved by directly opposing the balance wheel with an additional force of inertia, said opposition being possibly effected, in the preferred embodiment as well as in another, at the end of the backward stroke as well as at in the end of the forward stroke. 7

In the preferred embodiment which has been described, as Well as in any other, it is possible to conceive modifications of the driving connection between the fork and the damping member, for instance as indicated in Figs. 12 and 13, by securing to the fork two symmetrical pins 17a and 1711 between which the elongated nose in of the damper is engaged with the compulsory condition that the stroke of a pin 17a exceeds the space not occupied by the nose between these two pins; or also, as indicated in Figs. 14 and 15 without modifying a normal fork by using a movable damper formed with two symmetrical stamped lugs bent at right angles and which constitute abutment faces the: and 18b for the toe 7b of the guard pin 10, with the compulsory condition that the stroke of the engaging points of the toe exceed the space which is left free between these points and the toe 7b.

Obviously, the device which is the object of the invention may be applied to any type of timepieces, watches, clocks and the like, either with a lever escapement, a Roskopf escapement or any other.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. In a timepiece having an escapement mechanism provided with a reciprocatory movable part in said escapement mechanism, and a balance wheel operatively driven from said escapement mechanism through said part; an automatic device for regulating the amplitude of the oscillations of said balance wheel, said device comprising in combination a damping member freely supported for reciprocatory movement relative to the mechanism of the timepiece, a lost motion connection between said damping member and said reciprocatory movable part, the operative length of travel of said lost motion being shorter than the stroke of said reciprocatory part, whereby said damping member is moved to and fro by said reciprocatory movable part, and driving means operatively connected to said balance wheel and adapted to further drive said damping member at the end of at least one halfperiod of oscillation of said balance wheel, whenever the amplitude of said oscillation exceeds a predetermined value, whereby the extent of the amplitude of the balance wheel is maintained constant by the inertia opposed by said damping member to the portion of the oscillation in excess of said predetermined value.

2. In a timepiece according to claim 1, adapted to operate in a timepiece having an escapement lever, wherein said damping member is constituted by a blade mounted for pivotal movement in its own plane on an axis arranged between the axes of said lever and said balance wheel, respectively.

3. In a timepiece according to claim 1 adapted to operate in a timepiece having an escapement lever, wherein said damping member is constituted by a blade mounted for pivotal movement in its own plane on an axis arranged between the axes of said lever and said balance wheel, respectively, said damping member being formed with a depending nose adjacent said balance wheel, said driving means being constituted by a driving finger carried by said balance wheel and adapted to engage said nose.

4. In a timepiece according to claim 1, adapted to operate in a timepiece having an escapement lever, wherein said damping member is constituted by a blade mounted for pivotal movement in its own plane on an axis arranged between the axes of said lever and said balance wheel, respectively, said damping member being formed with a depending nose adiacent said balance wheel, said driving means being constituted by a driving finger carried by said balance wheel and adapted to engage said nose, said nose of said blade being asymmetrically bevelled so that said driving finger is able to engage said nose every other stroke only.

5. In a timepiece according to claim 1, adapted to opcrate in a timepiece having an escapement lever, wherein said clamping member is constituted by a blade mounted for pivotal movement in its own plane on an axis arranged between the axes of said lever and said balance wheel, respectively, said lost motion connection between said damping member and said escapement lever being constituted by a pin rigid with the fork of said escapement lever and an aperture through said blade, said finger having a portion thereof engaged in said aperture and adapted to hit against opposite inner edges of said aperture, the distance between said opposite edges being greater than said portion of said finger.

6. In a timepiece according to claim 1, adapted to operate in a timepiece having an escapement lever, wherein said clamping member is constituted by a blade mounted for pivotal movement in its own plane on an axis arranged between the axes of said lever and said balance wheel, respectively, said lost motion connection between said damping member and said escapement lever being constituted by two pins secured to the fork of said escapement lever and laterally embracing said blade so as to be adapted to hit against the lateral edges of said blade, the distance between said two pins being greater than the distance between said lateral edges of said blade.

7. In a timepiece according to claim 1, adapted to operate in a timepiece having an escapement lever, wherein said dam-ping member is constituted by a blade mounted for pivotal movement in its own plane on an axis arranged between the axes of said lever and said balance wheel, respectively, said lost motion connection between said damping member and said escapement lever being constituted by two lugs of said blade bent transversally of the place thereof, said two lugs freely embracing the conventional guard pin carrying heel of the fork of said escapement lever, the distance between said two lugs being larger than the width of said heel adapted to engage either of said lugs.

8. In a timepiece according to claim 1, with an abutment for said damping member, said abutment being adapted to limit the stroke of said damping member while allowing said lost motion to operate.

References Cited in the file of this patent FOREIGN PATENTS 286,908 Great Britain Mar. 15, 1928 

